Mutation are two types somatic and germ cell mutation...as there is mutation in germ cell it will alter the normal behavior and produce variation !
random fertilization also causes variation as different setup of genes meets with another different...so chances of variation increases !
and third crossing over is in meiosis when chiasmata forms....so in this two homologous chromosome attach to each other and on separation ... some part exchange so leads to variation !
        
             
        
        
        
Answer:
Since you didnt give an excerpt I can't answer. But I can give you advice. Read through and see If you can find, maybe less food or a higher predator or something like that
Explanation:
 
        
             
        
        
        
Answer:
B
Explanation:
Building more parks and houses will take away homes for animals living there.
 
        
             
        
        
        
Rna mrna trna <span>known as ribosomes; and finally, tRNA, or transfer </span>RNA<span>, that ferry amino acids to the ribosome to be assembled </span>